Self-Assembly of Reconfigurable By-Design Optical Materials with Molecular-Level Control

Abstract : Artificial structured materials hold high promise of providing a path to by-design optical materials with engineered optical properties. One of the major roadblocks for practical applications is the lack of efficient fabrication technology, which is also one of the grand challenges in nanotechnology in general. An efficient and scalable technique capable of producing large-area, three-dimensional (3D) structures is critically needed and self-assembly of nanoparticles offers an attractive solution to this problem. While there have been many studies on self-assembly of nanomaterials, precise molecular-level control of the assembly process over a large area or volume is yet to achieved. Here, we report a new approach to plasmonic nanoparticle self-assembly based on 3D shape-persistent cage molecules. Well-defined, rigid, 3D purely organic cage-like molecules have attracted great research attention due to their unique shape-persistency, structure-tunability, and chemical and thermal stability. However, to the best of our knowledge, utilizing rigid cage molecules as linkers to control the nanoparticle assembly has not yet been explored. The modular construction of cage molecules provides the design flexibility required to control the nanoparticle assembly process. Also, the shape-persistent nature of the molecules leads to highly stable and robust structures. In the following, we report successful self-assembly of gold nanoparticles using two different types of cage molecules as linkers. Our results shed light on how the molecular structures affect and thus can be used to control the self-assembly process.